Synthesis products of the chemical industry, which after forming for example by crystallizing, granulating, prilling, compacting, tabletting or pelleting and possible subsequent classification accumulate as bulk materials, are often still at a high temperature at the end of the production process. This heat has to be removed before they can be bagged and stored. Fluidized bed coolers and drum coolers are often used in order to cool the product, wherein air is used as the heat transfer medium. When cooling hygroscopic bulk materials, such as fertilizers and salts, it is necessary to dry the cooling air in order to prevent the product from absorbing moisture. Without drying the cooling air, there is the risk that the quality of the product will deteriorate. The hardness of the product drops with higher moisture content, whereby the shape previously imparted to the product can then be lost. In the most unfavorable case, bridge formation and clumping can occur.
Ambient air, which is used as cooling air, generally has a relative humidity which is too high for contact with hygroscopic materials. In order to achieve temperature and relative humidity values for the cooling air which are suitable for the cooling process, the cooling air passes through a conditioning process. There, the air is first cooled and the water contained therein is separated by condensation, absorption or adsorption. This lowers the dew point of the air. Then, the air is warmed back up to the point that the desired relative humidity for the cooling process is obtained. The air preconditioned in this manner is passed over the material to be cooled and removes heat therefrom without transferring humidity in the process. The provision of process cold and process heat for the conditioning process involves a large expenditure of energy.
Against the backdrop of rising energy costs, there exists the problem of proposing a method, and a system for carrying out the method, with lower energy consumption for cooling a solid, in particular a hygroscopic bulk material.